The following is a reprint of my post from 2016, with some edits:

Did Pope Paul IV say that a Pope can teach heresy or be a heretic? No, he did not. In the Apostolic Constitution Cum Ex Apostolic Officio (1559), Pope Paul IV issued penalties under the temporal authority of the Church against heretics and schismatics. The document speaks of three types of errors: the grave sin of heresy, the grave sin of schism, and also the sin of having deviated from the Catholic faith in some way, to some extent. This deviation cannot be to the extent of heresy or schism, since it is proposed as a different sin.

Neither can this deviation be apostasy, since anyone who can commit apostasy can also commits the lesser sins of heresy or schism. So the deviation is an error less than heresy or schism, either a personal sin (perhaps grave, but not gravely harmful to the Church), or an error on doctrine or discipline which is less than grave.

“Anyone who, before this date, shall have been detected to have deviated from the Catholic Faith, or fallen into any heresy, or incurred schism” [Pope Paul IV]

Of the three sins stated above, and referenced repeatedly throughout the document, the latter two — heresy and schism — are never applied by Pope Paul IV to the Roman Pontiff.

Yes, Pope Paul IV states that a Pope can commit the first of the three sins, deviating in some way, to some extent, from the Catholic Faith.

“the Roman Pontiff, who is the representative upon earth of God, and of our God and Lord Jesus Christ, who holds the fullness of power over peoples and kingdoms, who may judge all and be judged by none in this world, may nonetheless be contradicted if he be found to have deviated from the Faith.” [Ibidem]

Notice, first of all, the teaching that the Pope may be judged “by none in this world”. And that same teaching is found in the Constitution Unam Sanctam, a document of Pope Boniface VIII, which was confirmed by the Fifth Lateran Council (“the same Constitution, being approved by the sacred Council, we renew and approve.”). So it is never correct to say, under any excuse or explanation whatsoever, that anyone on earth — whether Cardinal, or Bishop, or emperor, or self-exalting online commentator — may call the Pope a heretic or apostate.

It is well established, so I don’t need to treat the subject at length, that each Pope is a fallen sinner, and that his teachings are only infallible if they meet certain conditions. So sins and errors, of some types and to some extent, are possible. Saint Peter erred by eating only with Christians who were converts from Judaism (thereby continuing a Mosaic practice, despite the dispensation of the Old Testament disciplines by Christ). And Saint Paul corrected him.

[Galatians]
{2:11} But when Cephas had arrived at Antioch, I stood against him to his face, because he was blameworthy.
{2:12} For before certain ones arrived from James, he ate with the Gentiles. But when they had arrived, he drew apart and separated himself, fearing those who were of the circumcision.
{2:13} And the other Jews consented to his pretense, so that even Barnabas was led by them into that falseness.
{2:14} But when I had seen that they were not walking correctly, by the truth of the Gospel, I said to Cephas in front of everyone: “If you, while you are a Jew, are living like the Gentiles and not the Jews, how is it that you compel the Gentiles to keep the customs of the Jews?”

So there is a clear example of a Pope, the very first Pope, deviating from the Catholic faith, though certainly not to the extent of heresy. If there had been an internet during the time of Peter and Paul, I’m sure many internet commentators would have rashly, falsely, sinfully accused Peter of heresy. But in truth, not every error which is in some sense a deviation from the Catholic faith is so grave as to qualify as heresy.

A deviation means going slightly off course — not lost, not opposing the true faith, not corrupting doctrine or discipline. A deviation is certainly substantially less than heresy or schism; it is an error which is not gravely harmful to the Church.

Thus, Pope Paul IV states that a Pope can possibly so deviate, and therefore be subject to fraternal correction, as in the case of Peter and Paul. But I should add that the vast majority of internet commentators, who have so readily and loudly rebuked Pope Francis, in many ways for many reasons, are not qualified to teach Catholicism to school children, and have not studied the Faith thoroughly enough to be able to distinguish error from doctrine. They themselves are guilty of many heresies, not the least of which is the rejection of the dogma that every Pope has the gift of truth and a never-failing faith [Vatican I].

As the document of Pope Paul IV continues, he lists many different persons in authority, who might possibly fall into heresy or schism, including Patriarchs, Cardinals, Bishops, and other Church officials — but never the Roman Pontiff — as well as dignitaries from secular society, up to and including the emperor. All these persons, Pope Paul IV allows might commit heresy or schism, and therefore would fall under the penalties of the document. But he never adds the Roman Pontiff to the list of persons susceptible to such sins. You can read the document for yourself here.

Finally, Pope Paul IV considers the case of the Roman Pontiff, but even then, he NEVER proposes even the possibility that a Pope might commit heresy or teach heresy. He carefully describes only the case of a person who commits heresy while he is not Pope, and then he states that the election of such a person is invalid.

Therefore, the claim that this document of Pope Paul IV teaches or admits the possibility of an heretical Pope is utterly false.

Now some foolish persons, wishing to find an excuse to reject Pope Francis, might try to claim that he (or some other Pope they dislike) committed heresy prior to his election, and that his election is invalid. But such is not the case. The decree of Pope Paul IV that the election of a future Pope would be invalid if the elected man had ever, at any time prior to his election, committed heresy, was of the temporal authority, and that decree has not been continued by subsequent Popes and Councils.

The election of Pope Francis falls under the decree of Pope Saint John Paul II, Universi Dominici Gregis, which is still in force today. Pope Saint John Paul II nullified all past decrees on the topic, so that his document would supersede any past rules and rulings. And he established only three conditions for a valid Pope: 1. valid election, 2. ordination as Bishop (before or after election), 3. and that the elected person freely accept the office.

Furthermore, since the Church is indefectible, God never permits any person who is an antipope (a false claimant to the papacy) to be accepted by the Bishops and dioceses of the world as if he were the Vicar of Christ. Pope Francis has been so accepted, and so he cannot possibly be an antipope, nor an invalid Pope.

It is dogma that the Church is indefectible; therefore, it is proximate to heresy to say that an invalid Pope (invalid election or invalid for some other reason) can be accepted by the body of Bishops. Pope Francis has been accepted as Pope by the body of Bishops, therefore he is necessarily a valid Pope. And since every Pope has the gift of a never-failing faith, from the prevenient grace of God, no Pope can become invalid as no Pope can commit the sins of apostasy, heresy, or schism.

Yes, Pope Francis has many detractors, but so did other valid Popes in the past. Pope Francis is the Vicar of Christ, the Supreme Pontiff of the one true Church, and the grace of God prevents him from teaching any heresy at all and from committing the sin of heresy at all.

My reply to those who use ex officio to condemn Pope Francis:

1. The document in question is a decree under the temporal authority. It does not contain an exercise of Papal Infallibility. And this is absolutely clear from the fact that things said, in the document, to continue in perpetuity in the Church have not so continued. Subsequent Popes and Councils have not retained all of these rules. Infallible teachings are unchangeable. Decisions on discipline are changeable and dispensable.

2. A careful reading of the document reveals that Pope Paul IV never states or implies that a Pope is capable of believing, asserting, or teaching any heresy. In fact, he carefully avoids including the Roman Pontiff whenever he gives a list of persons to be corrected or counteracted if they should teach material heresy or commit the sin of formal heresy.

3. Material heresy refers to ideas; formal heresy refers to a sin committed by a person. No person is properly called a “material” heretic.

4. The First Vatican Council infallibly taught that each Pope has the gift of truth and of a faith that cannot fail.

“Indeed, their apostolic teaching was embraced by all the venerable fathers and reverenced and followed by all the holy orthodox doctors, for they knew very well that this See of St. Peter always remains unblemished by any error, in accordance with the divine promise of our Lord and Savior to the prince of his disciples: ‘I have prayed for you that your faith may not fail; and when you have turned again, strengthen your brethren’ [Lk 22:32].

“This gift of truth and never-failing faith was therefore divinely conferred on Peter and his successors in this See so that they might discharge their exalted office for the salvation of all, and so that the whole flock of Christ might be kept away by them from the poisonous food of error and be nourished with the sustenance of heavenly doctrine. Thus the tendency to schism is removed and the whole Church is preserved in unity, and, resting on its foundation, can stand firm against the gates of hell.” [First Vatican Council]

Therefore, no Pope can commit the sins of apostasy, or heresy, or schism, nor can any Pope teach heresy or other grave error, nor can any Pope gravely harm the Church by a decision of discipline.

Ronald L Conte Jr